The results of the default device stop and domain power off governor functions for generic PM domains, default_stop_ok() and default_power_down_ok(), depend only on the timing data of devices, which are static, and on their PM QoS constraints. Thus, in theory, these functions only need to carry out their computations, which may be time consuming in general, when it is known that the PM QoS constraint of at least one of the devices in question has changed.

Use the PM QoS notifiers of devices to implement that. First, introduce new fields, constraint_changed and max_off_time_changed, into struct gpd_timing_data and struct generic_pm_domain, respectively, and register a PM QoS notifier function when adding a device into a domain that will set those fields to 'true' whenever the device's PM QoS constraint is modified. Second, make default_stop_ok() and default_power_down_ok() use those fields to decide whether or not to carry out their computations from scratch.

The device and PM domain hierarchies are taken into account in that and the expense is that the changes of PM QoS constraints of suspended devices will not be taken into account immediately, which isn't guaranteed anyway in general.

+ genpd->cached_power_down_ok = true; + /* * If the computed minimum device off time is negative, there are no * latency constraints, so the domain can spend arbitrary time in the -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo [at] vger More majordomo info at http://vger.kernel.org/majordomo-info.htmlPlease read the FAQ at http://www.tux.org/lkml/